By now, the fact that Apple is holding a press event on October 23 is old news. It's widely agreed that the long-rumored smaller iPad will finally be unveiled. But it's likely that the iPad Mini isn't the only thing that Apple will have up its sleeve. Expect to see at least one new Mac grace the stage during Tuesday's event.

There are a couple of reasons I'm confident that we'll see new Macs. First off, they're overdue -- Apple refreshed MacBooks last summer, but the desktop models are still running 2011 Intel chips. Secondly, this is a great time for Apple to play spoiler: Microsoft is launching Windows 8 next Friday. It makes plenty of sense for Apple to try to dampen some of that thunder with news for the Mac stalwarts.

Of course, the rumor mill is far from a consensus as to which model will receive an update. Rather than try to predict what Apple might do, following is the status, rumor-based or otherwise, of each Mac system that has not yet received an update this year.

iMac

Last update:May 3, 2011Latest rumor:"Details of redesigned iMac surface in China"
Apple has traditionally updated its flagship desktop line on a fairly regular annual basis. Now approaching 18 months between updates, the iMac is due for a refresh to Intel's new Ivy Bridge CPU family. A Chinese forum post claiming inside information says we'll see a new 21.5-inch iMac soon, followed later by a new 27-inch model. Fans are clamoring for a Retina screen on Apple's signature desktop, though it's unclear if such a large high-res screen will result in an impossibly high price.